An extract prepared from 200 adult female scabies mites was used for prick and intracutaneous testing in twelve patients with previous scabies infestation, as well as in six healthy controls and three persons with skin sensitivity to Dermatophagoides pteronyssinus who had never had scabies before. Seven individuals who had had scabies less than a year prior to the testing had positive intracutaneous (immediate type) reactions, whereas all the five who had had scabies more than a year before had negative reactions. The prick tests were negative in all cases. No skin reactions could be evoked in the controls. The passive transfer, or Prausnitz-Küstner, test was positive with the scabies mite extract and serum from three of five patients tested on one healthy individual, and with both of two sera tested on a second healthy individual. These findings indicate that immediate type hypersensitivity reactions may occur with scabies infection.